SOME COMMON BIRDS USEFUL TO THE FARMER.

By F. E. L. Beal, Assistant Biologist.

Note.—The habitat, food habits, and economic relation to agriculture of more than 50 birds common to farming sections are discussed in this bulletin. It supersedes Farmers’ Bulletin 54.

U.S. DEPARTMENT OF AGRICULTURE Farmers’ Bulletin 630

Contribution from the Bureau of Biological Survey, Henry W. Henshaw, Chief. February 13, 1915.

CONTENTS.

INTRODUCTION.

Whether a bird is beneficial or injurious depends almost entirely upon what it eats. In the case of species which are very abundant, or which feed to some extent on the crops of the farmer, the question of their average diet becomes one of supreme importance, and only by stomach examination can it be satisfactorily solved. Field observations are at best but fragmentary and inconclusive and lead to no final results. Birds are often accused of eating this or that product of cultivation, when an examination of the stomachs shows the accusation to be unfounded. Accordingly, the Biological Survey has conducted for some years past a systematic investigation of the food of those species which are most common about the farm and garden.

Within certain limits birds eat the kind of food that is most accessible, especially when their natural food is scarce or wanting. Thus they sometimes injure the crops of the farmer who has unintentionally destroyed their natural food in his improvement of swamp or pasture. Most of the damage done by birds and complained of by farmers and fruit growers arises from this very cause. The berry-bearing shrubs and seed-bearing weeds have been cleared away, and the birds have no recourse but to attack the cultivated grain or fruit which have replaced their natural food supply. The great majority of land birds subsist upon insects during the period of nesting and moulting, and also feed their young upon them during the first few weeks. Many species live almost entirely upon insects, taking vegetable food only when other subsistence fails. It is thus evident that in the course of a year birds destroy an incalculable number of insects, and it is difficult to overestimate the value of their services in restraining the great tide of insect life.

In winter, in the northern part of the country, insects become scarce or entirely disappear. Many species of birds, however, remain during the cold season and are able to maintain bike by eating vegetable food, as the seeds of weeds. Here again is another useful function of birds in destroying these weed seeds and thereby lessening the growth of the next year.

In the following pages are discussed the food habits of more than 50 birds belonging to 12 families. Many are eastern forms which are represented in the West by slightly different species or subspecies, but unless the food habits differ they are not separately described. In some cases specific percentages of food are given, but for the most part the statements are made without direct reference to the data on which they are based.[1]

[1] Farmers’ Bulletins describing the food habits of wild birds and groups of birds, or presenting methods of attracting them about our homes have been issued as follows:

54. Some Common Birds in their Relation to Agriculture, by F. E. L. Beal, 1897. The present bulletin is largely a revision of this bulletin and supersedes it.

383. How to Destroy English Sparrows, by Ned Dearborn, 1910. This bulletin has been superseded by Farmers’ Bulletin 493.

450. Our Grosbeaks and Their Relation to Agriculture, by W. L. McAtee, 1911.

493. The English Sparrow as a Pest, by Ned Dearborn, 1912.

497. Some Common Game, Aquatic, and Rapacious Birds in Relation to Man, by W. L. McAtee and F. E. L. Beal, 1912.

506. Food of Some Well-known Birds of Forest, Farm, and Garden, by F. E. L. Beal and W. L. McAtee, 1912.

513. Fifty Common Birds of Farm and Orchard, prepared under the direction of Henry W. Henshaw, 1913. This bulletin was issued with illustrations in color, and the demand for it was so enormous that it is no longer available for free distribution. Copies may be had for 15 cents (postage stamps not accepted) of the Superintendent of Documents, Government Printing Office.

609. Bird Houses and How to Build Them, by Ned Dearborn, 1914.

621. How to Attract Birds in Northeastern United States, by W. L. McAtee, 1914.

The parts of this bulletin relating to the crow and blue jay were contributed by E. R. Kalmbach, and the discussion of the nighthawk is by W. L. McAtee, both of the Bureau of Biological Survey.

THE BLUEBIRDS.

The eastern bluebird[2] (fig. 1), one of the most familiar and welcome of our feathered visitors, is a common inhabitant of all the States east of the Rocky Mountains from the Gulf of Mexico to southern Canada. In the Mississippi Valley it winters as far north as southern Illinois, and in the East as far as Pennsylvania. It is one of the earliest northern migrants, and everywhere is hailed as a harbinger of spring. Very domestic in habits, it frequents orchards and gardens, and builds its nests in cavities of trees, crannies in farm buildings, or boxes provided for its use.

[2] Sialia sialis.

The bluebird has not been accused, so far as known, of stealing fruit or of preying upon crops. An examination of 855 stomachs showed that 68 per cent of the food consists of insects and their allies, while the other 32 per cent is made up of various vegetable substances, found mostly in stomachs taken in winter. Beetles constitute 21 per cent of the whole food, grasshoppers 22, caterpillars 10, and various other insects 9, while a number of spiders and myriapods, about 6 per cent, comprise the remainder of the animal diet. All these are more or less harmful, except a few predacious beetles, which amount to 9 per cent. In view of the large consumption of grasshoppers and caterpillars we may at least condone this offense, if such it may be called. The destruction of grasshoppers is very noticeable in August and September, when these insects make up about 53 per cent of the diet.

It is evident that in the selection of its food the bluebird is governed more by abundance than by choice. Predacious beetles are eaten in spring, as they are among the first insects to appear; but in early summer caterpillars form an important part of the diet, and these are later replaced by grasshoppers. Beetles are eaten at all times, except when grasshoppers are more easily obtained.

So far as its vegetable food is concerned the bluebird is positively harmless. The only trace of any useful product in the stomachs consisted of a few blackberry seeds, and even these probably belonged to wild rather than cultivated varieties. Following is a list of the various seeds which were found: Blackberry, chokeberry, juniperberry, pokeberry, partridgeberry, greenbrier, Virginia creeper, bittersweet, holly, strawberry bush, false spikenard, wild sarsaparilla, sumac (several species), rose haws, sorrel, ragweed, grass, and asparagus. This list shows how little the bluebird depends upon the farm or garden to supply its needs and how easily, by encouraging the growth of some of these plants, many of which are highly ornamental, the bird may be induced to make its home on the premises.

Two species of bluebirds inhabit the Western States—the mountain bluebird[3] and the western bluebird.[4] In their food habits they are even more to be commended than their eastern relative. Their insect food is obtainable at all times of the year, and the general diet varies only in the fall, when some fruit, principally elderberries, is eaten, though an occasional blackberry or grape is also relished. In an examination of 217 stomachs of the western bluebird, animal matter (insects and spiders) was found to the extent of 82 per cent and vegetable matter to the extent of 18 per cent. The bulk of the former consists of bugs, grasshoppers, and caterpillars. Grasshoppers, when they can be obtained, are eaten freely during the whole season. Caterpillars also are a favorite food and are eaten during every month of the year; March is the month of greatest consumption, with 50 per cent, and the average for the year is 20 per cent. Two stomachs taken in January contained 64 and 50 per cent, respectively, of caterpillars. Beetles also are eaten and comprise mostly harmful species.

[3] Sialia currucoides.